Poor Man's TimerOften during testing of certain equipment and components, you would like to keep track of the elapsed time in hours, minutes and seconds. There are some nice commercial digital timers and counters available for just this sort of application. However, . . . Hobby Circuit designed by David Johnson P.E.-August, 2008

Picxie 2 8x8 Animated LED Signboard - The firmware supplied incurrent sourcecode archive is VERY BASIC. I do intend to draw more patterns. However, a vast workload coupled with possible emigration has putfinished firmware on hold. Please do go ahead and build this circuit thoughsupplied firmware is fully functional. You can have hours of fun designing your own patterns and effects!UsesPIC16F84 __ Designed by Lewin A.R.W. Edwards

PID Temperature Controller - What's a PID controller? PID stands for "proportional integral differential" and relates to a process which seeks to continuously correct the error between a measured variable and a desired setting by calculating an appropriate correction process. In practice, it can largely avoid the large overshoots and undershoots that occur in simple temerature control systems.__ SiliconChip

Planet Jupiter Receiver - How would you like to try some basic radio astronomylistening to the bursts of noise originating from the planet Jupiter, or from the Sun? You don't need a lot of fancy equipment to do this, just the simple shortwave receiver described here. It?s hooked up to a basic dipole antenna (which we describe as well) and to the sound card in your PC, so that you can print out "chart recordings" of the noise signals.__ SiliconChip

Plant Minder - PIC Project The PIC12F615 was perfect for this project. It runs off a 3 volt lithium cell. The unit is self calibrating. Just wait until your plant needs watering, insert the battery, and place in the soil. This sets the threshold for sensing dry soil. When the soil dries out to this point, the unit begins 'chirping' about every 20 minutes. __ Designed by Luhan MonatMesa Arizona

Playback Adaptor for CD-ROM Drives; Pt.2 - Last month, we published the circuit details of our new CD-ROM Player Adaptor and described its operation. This month, we show you how to build it.__ SiliconChip

PLL IC Forms Simple Circuit Digital Phase Shifter - 01/04/96 EDN-Design Ideas A phase shifter is a vital block in some signal-processing and clock-distribution applications. Another important application is in benchmarking digital phase detectors. The circuit in Figure 1, an especially appropriate one for evaluating phase detectors, uses only two industry-standard ICs (CD4046 and LM311]. It relies on digital PLL techniques __ Circuit Design by Haldun Karaca, DE University Bornova, Izmir, Turkey

Pocket AV Generator - There are not many video test pattern generators on the market and the ones that are cost big dollars. This kit is a fraction of the cost of commercially available units, it's portable and it has audio outputs as well!__ SiliconChip

Poor Man's Timer - Often during testing of certain equipment and components, you would like to keep track of the elapsed time in hours, minutes and seconds. There are some nice commercial digital timers and counters available for just this sort of application. However, . . . Hobby Circuit designed by David Johnson P.E.-August, 2008

Position Detectors provide Motor-control logic - 05/24/01 EDN-Design Ideas In the circuit of Figure 1 , assume that a brush-type dc motor must drive a load back and forth between two endpoints on a lead screw. Optical sensors determine end of travel, and an SPDT switch selects to which end to send the load. The sensors themselves supply all the necessary directional logic, and a TRIAC powers the motor with the necessary polarity of half-wave pulses from the 13. PDF have several circuits, scroll for this one __ Circuit Design by Steve Pomeroy and Russell Hedges, Elgar Corp, San Diego, CA

Pot Adjusts LCD's Contrast - 02/04/99 EDN-Design Ideas NOTE
: Page includes
several designs. Scroll to find this one. You can use a digitally controlled potentiometer for many purposes. In this example, you can use the device to regulate the contrast of a standard (such as two lines by 40 characters] LCD. You can use the circuit in Figure 1 in a portable test system, in which you need to change the contrast of the LCD as a function of the viewing angle. You choose the contrast setup __ Circuit Design by Jef Collin, CSE Systems, Turnhout, Belgium

Potentiometer Autonulls OpAmp - 10/22/98 EDN-Design Ideas Op-amp applications that need the highest possible dc accuracy are generally best served by CMOS
chopper-stabilized amplifiers, such as the LTC1050. But high-speed, low-noise applications may require high-performance rockets, such as the 700-MHz LT1226. So what to do for applications __ Circuit Design by Stephen Woodward, University Of North Carolina, Chapel Hill, NC

Potentiometer Controls LCD Bias - 03/17/94 EDN-Design Ideas Designers of pen-based computers can easily relegate some controls that were previously mechanical, such as switches and potentiometers, to on-screen icons. For example, the circuit in Fig 1 shows one way that digital logic can control the -24V-dc LCD bias using two general-purpose I/O command lines. The DS-1669 from Dallas Semiconductor __ Circuit Design by Michael Cortopassi, Dauphin Technology, Lombard, IL

Potentiometer controls phase shift - 02/15/96 EDN-Design Ideas You can use dual, quad, or hex potentiometers to put all phase-shift sections under control of a microprocessor, as in Figure 2. The DS1806 hex digital . __ Circuit Design by Rick Downs, Dallas Semiconductor Dallas, TX

Potentiometer Programs & Stabilizes Voltage Reference - 05/30/02 EDN-Design Ideas The potentiometer portion of a mixed-signal, digitally programmable potentiometer adds variability to an analog circuit, and its controls provide programmability. You can use a potentiometer in two ways in an analog circuit. You can use it as a two-terminal variable resistance, or rheostat, or as a three-terminal resistive divider. / (schematic / circuit added 11/03] __ Circuit Design by Chuck Wojslaw, Catalyst Semiconductor, Sunnyvale, CAMay 30, 2002

Potentiometers Enable Programmable Biquadratic Filter - 07/22/04 EDN-Design Ideas Of the many types of analog filters available to designers, few allow easy adjustments of the filter parameters. The biquadratic, or biquad, filter is an exception, however. You can change that filter's corner frequency (ω0], Q, and gain (H] by adjusting the values of three resistors. For that purpose, the lowpass biquad circuit of Figure 1 includes three digital potentiometers configure __ Circuit Design by Deborah Mancuso and Donald Schelle, Maxim Integrated Products, Sunnyvale, CA

Power Controller - PIC Project This device controls the power to 8 individual outlets. There are 16 power levels available for each one. Connection is made via 9600 baud serial using a din-5 connector. A single byte sets the power level for any of the 8 channels. Also, a global command sets all the power levels at once. __ Designed by Luhan MonatMesa Arizona

Precision 10V DC Reference for Checking DMMs - Have you ever checked the calibration of your digital multimeter? Yeah, we knowyou haven't because there is no easy (read cheap) way of doing it. But now you can with this precision DC voltage reference that can be built in a few hours. Without any need for adjustment it will provide you with a 10.000V DC source accurate to within ?3mV, ie, an accuracy of ?0.03%.__ SiliconChip

Precision Amplifier with Digital Control - This circuit is similar to the preceding circuit of the attenuator. Gain of up to 100 can be achieved in this configuration, which is useful forb signal conditioning of low output...__ Electronics Projects for You

Precision Attenuator with Digital Control - This is a circuit for a low cost precision attenuator with digital control. __ Electronics Projects for You

Precision Digital AC Power Controller - SCRs and TRIACs are extensively used in modern electronic power controllers—in which power is controlled by means of phaseangle variation of the conduction period. Controlling the phase angle can be made...__ Electronics Projects for You

Precision Digital Altimeter - The current concept incorporates a wireless transmitter and receiver and is thought to be used for remote controlled airplanes or appliances with two separate parts. In other words, we have one dedicated transmitter (acquisition, filtering) and one dedicated receiver part (user-interface, look-up table, calibration, storage) , capable of being connected

Precision Temperature Logger & Controller, Part 1 - This Temperature Logger & Controller is based on the Dick Smith Electronics Q1437 digital thermometer. It records & displays two temperature channels once a second on a PC over a period of up to 12 hours. With appropriate thermocouples, temperatures from -200?C to +1300?C can be recorded, with the display range, resolution, and temperature program adjustable in real time while the data is being logged.__ SiliconChip

Printer Port Hardware Simulator - Simple circuit let's you test printers or other hardware that connects to a PC's parallel port without the need for a PC or software.__ SiliconChip

Printer Port Records Digital Waveforms - 06/18/98 EDN-Design Ideas - (File includes several circuitsscroll to find this one) To record or capture special waveforms, those that appear once or have no fixed frequency, the usual technique is to use a logic analyzer or a storage oscilloscope. However, these tools are very expensive. Moreover, because of limited memory, a storage scope can record fewer than 1000 samples. The technique presented here provIdeas an alternative method to recording digital waveforms. The idea is to use the PC's printer port to sample waveforms, and the PC's memory to store data. __ Circuit Design by Dean Shen, Dycam Inc, Chatsworth, CA

Priority Encoders Slip Into FPGA - 02/17/94 EDN-Design Ideas The standard 8-to-3 priority encoder's design, in maximal canonical form (such as the 74148) , suffers from drawbacks when you try to use the design as a macro in a large digital project. The drawbacks are: The number of inputs to the gates varies from two to nine; If any of the inputs develops a stuck-at-zero or stuck-at-one fault, such a fault is difficult to detect; and Reconfiguring the design to suit a fault-tolerant design is difficult. __ Circuit Design by Swapnajit Mittra, Baharat Electronics, Bangalore, India